Unmanned underwater vehicles offer a variety of possibilities for underwater works and can reach greater working depths compared to manned underwater vehicles and work in environments that are too dangerous for manned systems or divers. Autonomous underwater vehicles (AUV) have their own power supply and do not require communication with a human operator during their mission. They rather follow a prescribed mission program. Upon completion of the mission program, the autonomous underwater vehicle also submerges autonomously and is recovered for example by a mother ship.
The autonomous underwater vehicle is usually equipped with suitable sensors, such as sonar sensors. As opposed to remotely operated underwater vehicles (ROV=“remotely operated vehicle”), which are adapted more specifically for missions with localized inspections, for example of concrete underwater objects, under real-time conditions, autonomous underwater vehicles are as a rule driven by a stern propeller and are more specifically adapted for extensive or large-scale reconnaissance under water. Autonomous underwater vehicles are for example advantageously used for cable and pipeline inspection or to search out mines.
During the mission of an autonomous unmanned underwater vehicle, recording the measurement results and if required transmitting them wirelessly to the mother ship is known. The transmission of information during the mission of the submerged underwater vehicle is however limited and only possible when the distance between the autonomous underwater vehicle and the mother ship is short.
In order to increase the range of data transmission to the mother ship, JP 62008895 A discloses an underwater working system for remote-controlled underwater vehicles (ROV), in which a supply and control cable of an unmanned remote-controlled underwater vehicle (ROV) is connected to a radio buoy floating at the surface of the water. The radio buoy is equipped with a radio antenna and a receiver and emitter unit. By way of the radio connection with the radio buoy and the supply cable between the radio buoy and the underwater vehicle, the underwater vehicle is remote-controllable by the mother ship.
By relaying the connection between the mother ship and the remote-controlled underwater vehicle via the radio buoy, the remote-controlled underwater vehicle can operate in its localized work space at a greater distance from the mother ship than would be possible with a direct connection of the underwater vehicle with the mother ship.
WO 91/13800 discloses a system for underwater reconnaissance with autonomous underwater vehicles having an identical configuration and comprising respectively one combustion motor and one electric motor as well as a battery. One of the underwater vehicles is located at the surface of the water, the combustion motor loading the battery. During this phase, the underwater vehicle located at the surface is in radio contact with a mother ship. The other underwater vehicle works under water and is driven by its electric motor. The two underwater vehicles communicate wirelessly via an acoustic or optical connection. As soon as the battery of the active submerged underwater vehicle is empty, the underwater vehicles change places. Images are transmitted via the wireless connection from the active underwater vehicle to the mother ship, namely first via the wireless connection with the surface underwater vehicle and subsequently via the radio connection of the surface underwater vehicle.
This known underwater work system is provided for local inspection of the underwater world, for example to explore a wreck. This known statically operating underwater work system is unsuitable for extensive underwater reconnaissance, for example for reconnoitering an underwater area in the context of mine clearance or for inspecting long pipelines.
WO 2012/037174 A2 discloses a buoy and a system for monitoring divers and other underwater objects. The buoy can monitor a diver and obtain position information about the diver and use that information in order to position itself accordingly for further monitoring.
The buoy can use an acoustic communication device for communication with the diver and determine the position of the diver as well as biometric and other data.
In one embodiment, the buoy comprises a drive system and the diver can guide the buoy to an operating area by way of an acoustic communication module.
A merely acoustic communication is mandatory since a possible physical connection, for example by means of a rope or hose, is not authorized for security reasons. In addition, the data transmission rate is limited by the acoustic communication, so that real-time capabilities cannot be ensured.